UK researchers unveils solar-powered brine treatment process

A UK academic has proposed a new solar energy-driven process to convert brine produced by desalination plants. The process also removes carbon dioxide dissolved in the oceans ocean to reduce its damaging environmental impacts according to the researcher at Birmingham’s Aston University.

Philip Davies, of Aston’s School of Engineering and Applied Science, has devised a system that uses desalination plants as a sink, rather than a source of atmospheric carbon dioxide, and help to neutralise ocean acidity.

Davies’s model harnesses solar energy to converts magnesium chloride in waste brine to magnesium oxide, which is discharged to the ocean. Due to its alkaline nature, this subsequently neutralises ocean acidity and gradually removes carbon dioxide through the conversion of magnesium oxide to bicarbonate, similar to ocean liming.

This approach would, according to Davies, increase the energy requirement of a plant by 50% but he has calculated that this increase would be offset by the carbon dioxide absorption capacity. His process would result in 0.4% of carbon dioxide emissions being absorbed which could open the way to double the current global desalination capacity.

Davies, said: “Not much energy is needed to decompose magnesium chloride in brine to magnesium oxide, which makes the use of solar energy potentially very attractive.” He added: “Lowering the energy required to dewater brine prior to decomposition would be a major environmental benefit. If we could find better ways to dewater the brine this would become very energy efficient as a means of avoiding carbon dioxide.”

Davies noted that rapid advances in desalination technology were making the dewatering of waste brine easier citing “improved membranes for membrane distillation and electrodialysis”.